The invention herein relates to an assembly for the infusion of medication into a patient in response to the patient's demand and based upon the patient's physiological condition. The invention herein is particularly related to a patient controlled analgesia system wherein the patient can request the administration of an analgesic agent, but the delivery of such analgesic agent is controlled by the system based upon the patient's physiological conditions, and more specifically, the patient's respiration rate. The system herein can also detect infiltration and/or occlusion of the infusion line leading to a peripheral vein of the patient for introducing medication to such peripheral vein.
Pain is often associated with the postoperative care patient. In the past, the most common method of delivering analgesic medication to a patient has been the administration of such medication by an attendant, such as a nurse, after the patient has requested such medication. In such procedures, patients have to bear unnecessary pain until an attendant becomes available to deliver the medication. The administration of such medication is usually performed with the introduction of the analgesic agent in a relatively greater than needed dosage, which will be sufficient to reduce the pain for a sufficiently longer time than necessary. The medication and dosage is dictated by a doctor's prescription. The patient receives an initially large dose of the analgesic agent which is usually more than the amount required to reduce the pain, but which is a sufficiently large amount so as to provide prolonged relief for a predetermined period. A problem associated with delivering such an initially large dosage of medication is that the volume may be sufficiently great that the patient, especially the post-operative patient, can have depressed physiological conditions, such as respiration rate and heart rate. Thus, the attendant or attending nurse must monitor the patient' s respiration rate and heart rate, to assure that the desired levels are maintained.
It would be desirable to provide an automatic medication introduction rate control system which would provide a sufficient amount of medication to a patient upon demand to overcome any pain, but which would monitor the physiological conditions of the patient so as to prevent introduction of medication when the patient's physiological conditions warrant not introducing such medication. It would also be desirable to have a system which would provide an indication when occlusion and/or infiltration of the infusion line has occurred. It would be greatly desirable to provide such systems which could be directly connected to the patient's venous system, and thereby be compatible with standard intravenous (IV) administration sets.